Many vehicles use mounted tanks to contain liquids necessary for vehicle operation. Such liquids include hydraulic oil, gasoline and water, as examples. Although it is believed that federal regulations require that such tanks be mounted internally on vehicles designed for highway or on-road use, off-road vehicles such as those used in the farming or construction industry often employ (and are permitted to employ) externally-mounted tanks, i.e., tanks visible and accessible to the operator. Off-road vehicles are subjected to vibration, sometimes severe, as they travel over uneven terrain and as they are operated.
A known approach to mounting a hydraulic tank to a vehicle such as a loader/backhoe having a pair of box-like chassis channels uses short, cylindrical tapped bosses welded to the relatively-thick plate forming a side of a channel. At one tank side, the tank has mounting ears and threaded fasteners extend through the ears and thread into respective bosses. It might be said that the tank is cantilever-mounted in that the tank center of gravity is spaced outwardly away from the mounting ears. While this approach is generally satisfactory, it is not without problems.
One problem is known as "oil canning" and occurs during normal vehicle operation. Even though the plate to which the bosses are welded is relatively thick, such plate flexes along lines which represent "stress risers," i.e., lines of high localized metal stress. Over time, this causes tiny fatigue cracks to form in the plate and the chassis channel is thereby weakened and may even fracture. And plate flexing is not the only problem.
Vibration occurring during normal vehicle operation causes what is known as fatigue cracking of the welds securing the threaded bosses to the plate. In an extreme case, weld cracking becomes so severe that a particular boss separates from the channel plate to which it is mounted and becomes ineffective in supporting the considerable weight of the tank and its contents.
And normal vehicle operation is not the only factor which can causes oil-canning and weld cracking. In one known tank mounting arrangement, a step is mounted on the tank outer edge lateral to the tank mounting ears. Such step is used by the operator to gain access to the vehicle cab and when alighting from the vehicle. When the step is so mounted and used, the operator's weight as well as that of the tank and its contents are cantilever-supported by the welded bosses.
Chassis channel cracking and weld breakage often lead to vehicle "downtime." That is, the vehicle must be taken out of service and repaired--during time spent in repair, the vehicle owner does not get the economic benefit of the monetary investment in the machine.
An improved structure and method for mounting a liquid-holding tank to a vehicle chassis in a way which eliminates "oil canning," weld cracking and other forms of metal fatigue would be an important advance in the art.